1. Field of the Invention
The invention is directed to a tri-fold row marker having three sections that are pivotally coupled to one another. The row marker has an extended working position and a retracted transport position.
2. Description of the Prior Art
Row markers are commonly attached to agricultural implements, such as planters and grain drills, to mark the field for the farmer's next pass. As implements have become wider row markers have become longer. The longer row markers have folded transport positions and extended working positions.
Bi-fold row markers have two pivot points, see U.S. Pat. No. 4,530,405. In the patent identified above, the bi-fold marker has an inner arm that is pivotally mounted to the planter toolbar and an outer arm that is pivotally coupled to the inner arm. A hydraulic cylinder manipulates the inner arm into and out of its horizontal working position and vertical transport position. The outer arm is extended by a cable that is coupled between the outer arm and the toolbar. As the hydraulic cylinder pivots the inner arm from its vertical transport position to its horizontal working position, the cable extends the outer arm so that it is in line with the inner arm when the row marker is in its working position.
As agricultural implements became wider tri-fold markers were developed having three pivot points, see U.S. Pat. Nos. 4,207,950, 4,449,590 and 4,986,367. In all three above-identified tri-fold designs, a single hydraulic cylinder is used to manipulate the folding and unfolding action of the row marker. In the first two designs, U.S. Pat. Nos. 4,207,950 and 4,449,590, a cable or chain is used to extend the outer arm during an unfolding operation in a manner similar to the above discussed bi-fold row marker. The cable or chain does not control the movement of the outer arm during the folding cycle, creating a high kinetic impact when the outer arm engages a stop located on the inner arm. In the third design, U.S. Pat. No. 4,986,367, a control arm is used to extend the outer arm.